Clamp for electrical connectors



Oct. 11, 1955 o. E. WESTBERG 2,720,633

CLAMP FOR ELECTRICAL CONNECTORS Filed June 12, 1953 j I II I UnitedStates Patent CLAMP FOR ELECTRICAL CONNECTORS Oscar E. Westberg,Williston, N. Dak.

Application June 12, 1953, Serial No. 361,299

3 Claims. (Cl. 339-75) This invention relates to clamps for holdingelectrical plug-and-socket type connectors in assembled and electricallyconnective relationship.

Electrical extension cords are widely used in connecting lamps,appliances, shop equipment and other movable electrical equipment toelectrical outlets. Connections between cords, as well as between cordand equipment, are commonly made by means of separable plug and socketmembers attached to the respective cord ends. The plug member provides apair of electrically conductive prongs which slide into correspondingslots in the socket member, where they are frictionally held in placeby, and make electrical contact with, springy conductive insertstherein. The two conductors of each of the two respective cords areattached respectively to the two prongs of the plug member and the twoinserts of the socket member at points within insulating coveringsforming the body portions of each of said plug and socket members.

It frequently happens that extension cords must be suspended fromoverhead appliances or outlets, moved about, pulled over and aroundobstructions, and generally subjected to stress during use. Thefrictional forces holding plug and socket connectors of such cords inconnected relationship are insufficient to withstand any but thelightest of such stresses, with the result that the connection is easilybroken. The plug and socket may be taped or wired together, but mustthen be laboriously untaped or cut apart before they can be separated.Various mechanical devices have been suggested for the purpose, butthese have been of complicated structure involving multiple parts; orthey have been unduly expensive, or difi'icult to apply or remove; orthey have proven impractical for other reasons.

It is therefore an object of the present invention to provide a simpleand economical but highly efiective clamp member which can be easily andquickly applied to and removed from a plug-and-socket connector; andwhich when applied thereto will remain firmly attached and will maintainthe elements of the connector in operable relationship under all usualoperating stresses.

The invention will now be described by reference to the accompanyingdrawing, in which Figures 1 and 2 illustrate in perspective two specificmodifications of the invention as applied to plug-and-socket typeconnectors, and Figures 3 and 4 are plan views of the two clamps ofFigures 1 and 2 respectviely.

The clamp of Figure 1 consists of the C-shaped spring member, the endsof the 0 being bifurcated, the two flattened fingers 11 of each of thebifurcated portions being open forwardly of the clamp and in the form ofa generally U-shaped segment of a substantially spherical surface, sothat they fit closely over the rounded ends 12, 13 of the socket member14 and plug member 15 of the connector and around the central tubularextrusions 16, 17 through which the cords or cables 18, 19 are passed.The spherical configuration of the finger members results in a firm gripbeing maintained by the or punching from a wide bar or sheet.

clamp 10 on the rounded ends of the connector, under the tension of theexpanded C-shaped spring member. The spring member may be made of anydesired thickness and width of stock and of any desired material, springsteel or spring bronze being highly acceptable. The fingers 11 inparticular, or the entire clamp if desired, may be coated with aprotective and decorative finish which may also be chosen to provideelectrical insulating qualities.

Alternatively, the U-shaped end sections and the C- shaped springsection may be made separately and of the same or different materials.For example, a metal spring member may be fitted with plastic or othernon-metallic finger-forming end members, held in place by rivets orother suitable means.

The modification illustrated in Figure 2 is designed to be applied tothe cords or cables rather than directly to the plug and socket. Thefingers 21 formed at the bifurcated ends of the C-shaped spring of clamp20 form a claw member at each end of the C-shape springs, said clawsfitting around the wires 28, 29 attached respectively to the socketmember 24 and the plug member 25, and pressing firmly against thetubular extensions 26 and 27 thereof to hold the plug and socket memberstogether in electrically connective relationship.

Clamps having rounded fingers 11 as shown in Figures 1 and 3 at one endof the C-shaped spring member and claw-shaped fingers 21 as shown inFigures 2 and 4 at the other end are applicable to certain types ofconnectors, and various other modifications of the invention will occurto those skilled in the art upon consideration of the disclosures hereprovided.

One advantage of the form of clamp illustrated in Figure 2 is that it isadapted to a wide variety of connectors, including those having endportions of irregular shape, since the finger members 21 attach to theelectrical cord rather than to the connector itself; whereas the fingermembers 11 of clamp 10 of Figure 1 are designed specifically for usewith connectors having rounded end areas. The clamp of Figure 2 may beformed from a segment of straight bar stock of uniform width, whereasthat of Figure 1 is more easily produced by cutting However the clamp ofFigure 1 is somewhat more readily formed than that of Figure 2 by simplepunch-press methods; it may be made of a uniform width strip of stock bymerely expanding the C-shaped clamp portion to the same width as thearea covered by the fingers 11 or by folding a wider strip to form thenarrower C-shaped spring section shown; and since most electricalextension cords are presently fitted with plug and socket members havinguniformly shaped rounded ends, it is capable of adequately wide-spreadapplication.

Having now described and illustrated specific embodiments of theinvention, but without limiting the invention thereto, what is claimedis as follows:

1. A clamp for maintaining plug and socket members of an electricalconnector in electrically connective relationship as herein described,said clamp comprising a single elongated fiat strip of spring metalpermanently formed into a C-shaped clamp having each of the ends of theC bifurcated to form fingers lying on opposite sides of the central axisof an inserted connector and said fingers being shaped to remain firmlyin place on said connector and to fit against the respective ends ofsaid connector under the spring tension afiorded by the expandedC-shaped spring member.

2. A clamp for maintaining plug and socket members of an electricalconnector in electrically connective relationship as herein described,said clamp comprising a single elongated spring member permanentlyformed into a C-shaped clamp having each of the ends of the C bi- 3 gfurcated to form fingers lying on opposite sides of the central axis ofan inserted connector and said'fingersbeing shaped to remain firmly-inplace on said connector and to fit against the respective ends of saidconnector under the spring tension afforded by the expanded C- shapedspring member, the fingers of 'at least one bi-' furcated end of saidC-shaped spring member being in the form of a U-shaped segment of asubstantially spherical surface.

'3. A clamp for maintaining plug and socket members of an electricalconnector in electrically connective relationship as herein described,said clamp comprising a onepiece C-shaped spring member having each ofthe ends of the C bifurcated to form fingers lying on opposite sides ofthe central axis of an inserted connector and said fingers being shapedto remain firmly in place on said connector and to fit against therespective ends of said connector under the spring tension afforded bythe expanded C-shaped spring member, the fingers of at least onebifurcated end of the C-shaped spring member being in the form of anopen-ended rounded claw capable of fitting tightly 0n the electricalcord attached to the plug and socket members of the inserted connector.

' References Cited in the file of this patent UNITED STATES PATENTS1,717,877 DOlier a June 18 ,1929 1,989,823 Raabe Feb. 5, 1935 2,461,427Kneebone Feb. 8, 1949

